The the NF originally started using the 20 seocnd TO, it was suggested that the players stand. It disappeared from any of the books after the first year. My guess is that someone, somewhere complained about players sitting during a 20 or 30 and it was changed.

Sound strange? Not as strange as you make think. A couple of years ago, during a state championship game, a player in the first space moved all the way down to the baseline and waved his hand to distract the shooter. The next year, the Fed added the 8 inch line that now is equired on every FT lane.

Bottom Lane Line
 

The bottom lane line was added to prevent players from standing near the baseline & getting a running start on their jump. Players would get a one or two steps before the jumped; thus giving them an advantage. Also, there was an issue of safety. As this player was jumping back into the other players, this caused concern over all players' safety.

Also, regarding your comment about standing on the end line & waving hands to distract the shooter - That is a violation (disconcerting to the shooter). Players lined up along the lane may not intentionally distract the shooter. This includes jestures, clapping, yelling at or talking to the shooter. The penalty is to award substitute throw if original is missed.

Re: Bottom Lane Line
 

Possibly but that's not how it was explained to us. The Chairman of the NF basketball Rules Committee is also our State Deputy Director. He explained the exact play that occurred that, although I may have forgotten some small details. But a player getting a running start was not the issue. I don't see how it would be possible to get a running start inside a 6' space.

Concern over players' safety because a player was jumping into them? Have you ever watched a basketball game? :)

In any case, neither reason makes any sense.

Yes, thank you. I am well aware of the rules concerning disconcertion.